Hydrogenation and coking of heavy petroleum fractions



Jan. 27, 1959 v. w. WEEKMAN, JR 2,871,182

HYDROGENATION AND COKING OF' HEAVY PETROLEUM FRACTIONS Jan. 27, 1959 v. w. WEEKMAN, JR 2,871,182

HYDROGENATION AND COKIN@ 0E HEAVY PETROLEUM FRACT'IONS Filed Aug. 17, 195e 2 'sheets-sheet 2 GASOLINE States 2,371,182 Patented Jan. 27, 1959 HYDROGENATIN AND COKING F HEAVY PETROLEUM FRACTIONS Vern W. Weekman, Jr., Rome, N. Y., assigner to Socony Mobil Oil Company, Inc., a corporation of New York Application August 17, 1956, Serial No. 604,749

9 Claims. (Ci. 20E-50) The present invention relates to the upgrading of heavy petroleum fractions and, more particularly, to the upgrading of long and short residua.

Heretofore, it has been common practice to upgrade heavy petroleum fractions by vis-breaking and coking. Conventional coking processes for upgrading heavy petroleum fractions, such as residua, require regular periodic shutdowns for the removal of the coke deposits from the coking unit. Conventional petroleum coke is diflicult to remove from the unit. `Conventional coking operations do not reduce the sulfur content of the liquid products appreciably. in addition, the liquid products produced in the conventional coking operations are usually highly unsaturated. Because of the high sulfur content of the liquid products from conventional coking processes, it is necessary to treat the liquid products to remove the sulfur.

The process of the present invention produces a very nely divided easily removed coke which can be removed continuously from the unit, thus imparting .continuity of operation to the process. v

Furthermore, 80-90 percent of the sulfur of the charge L stock is removed and the liquid products are much less unsaturated than the liquid products produced by conventional coking processes. Finally, the liquid products have a higher A. P. l. gravity than the charge stock, a greater yield of gasoline is obtained and the heavier than gasoline fractions have a higher Diesel index than corresponding liquid products produced by conventional colf.- ing processes.

The present invention provides for mildly hydrogenating the charge stock and coking the hydrogenated charge. The basic combination of operations, i. e., mild hydrogenation followed by coking of the hydrogenated charge stock, can be modified in many ways. For example, the heavier than gasoline fraction of the Coker eiliuent can be in part or wholly returned to the coker or to the hydrogenation unit. Similarly, the heavier than gasoline fraction of the coker effluent can be subjected to more severe hydrogenation. These and other advantages and modif.- cations of the basic concept of mildly hydrogenating colrer charge stock before coking will become apparent to those skilled in the art from the following description taken in conjunction with the drawings in which Figure l is a highly schematic flow-sheet illustrating mild hydrogenation of a heavy petroleum fraction such as a long or short residuum followed by coking of the hydrogenated charge stock, and

yFigure 2 is a highly schematic How-sheet illustrating mild hydrogenaticn of a heavy petroleum charge stock followed by colring of the hydrogenated charge stock in which the heavier than gasoline fraction of the coker effluent is subjected to severer hydrogenation.

In accordance with the principles of the present invention a heavy petroleum fraction suchvas a residuum can be mildly hydrogenated and then coked in accordance with the manipulation illustrated by the flow-sheet in Figure l. Thus, a heavy petroleum fraction, for example a rcsiduum having the following characterizing attributes:

I. B. P. F. (vac. assay) 494 10% point F 718 point F 952 59% 985 Gravity, A. P. l 15.7 Sulfur, Wt. percent 3.95

ows under reaction pressure from a source not shown through line 1. In the beginning and at other times during operation as is necessary hydrogen or gases containing at least 25 percent hydrogen liow under reaction pressure `from a source not shown through line 4 to line 1 under control of valve S. At other times hydrogen-containing recycle gas, obtained as hereinafter described flows from line 6 through line 7 under control of valve 8 to line 1. i

The mixture of heavy petroleum fraction and hydrogencontaining gas in the molar ratio of about 1.5 to 25 mols of hydrogen per mol of heavy petroleum fraction or about 300 to 5000 standard cubic feet of hydrogen per barrel of feed (s. c. f./b.) ows through line 1 under reaction pressure to coil 2 of heater 3.

In coil 2 of heater 3 the charge mixture of heavy petroleum fraction and hydrogen-containing gas is heated to a reaction temperature. The heated charge ows from coil 2 through line 9 to line 10. In line 10 the charge mixture containing the fresh charge stock is mixed with hot liquid recycle drawn from line 11 under control of Valve 12 by pump 13 through line 14 and discharged through line 15 into line 10.

`he mixture of charge mixture and hot liquid recycle iiows through line 10 to line 16.

When reaction conditions permit, e. g., when the temperature and quantity of recycle gas mixed with the fresh charge and the hot liquid recycle does not reduce the temperature of the mixed gas and oil below reaction temperature, recycle gas can be mixed with the fresh charge and the hot liquid recycle without heating the recycle gas by closing valve S and opening valve 17 in line 18. `On the other hand, a portion of the recycle gas can be mixed with the fresh charge and heated therewith and a portion can be introduced through line 18 under control of valve 17.

lThe reactor feed comprising fresh charge, e. g., residuum, and bot liquid recycle in the ratio of about 0 to l0 volumes of hot liquid recycle per volume of fresh charge and hydrogen containing gas in the ratio of about 0.5 to 25 mols hydrogen per mol of fresh charge and hot liquid recycle flows through line 16 through reactor 19. ln reactor 19 any snif-active catalyst can be used. For example, a mixture of cobalt and molybdenum oxides on a carrier or support such as alumina is preferred for mild hydro-genation resulting in hydrodesulfurization of the reaction mixture oil. Employing such sulf-active catalyst, the following reactor conditions have been found to give satisfactory results.

Temperature, F 600- 800 Pressure, p. s. i. g SOO-3000 Space velocity, v./v./hr 0.1- 10 Hydrogen, s c. f./b 300-5000 Recycle, s. c. f./b 0-5000 The reactor effluent leaves reactor 19 through line 20 through which it flows to the coking heater. It is preferred to maintain the reactor pressure in the coking heater and settler but the coking operation can also be carried out at pressures below those existing in reactor 19. Accordingly, the following conditions will exist in the coking step:

Temperature, F 800-1200 Pressure, p. s. i. g 0-3000 Hydrogen, s. c. f./b. 1 0-5000 1From the hydrogeuation reaction and/0r fresh hydrogen.

The remuant ,from ,reactor 19 ,ows through ...coking heater coil 21 in coking heater 22 and thence through line 23 to coke settler 24.

The coke produced bycoking p the; hydrogenated, i. e., at asllaiially djlllfllrized reactoreluentisfine and granular, 4"lhei ine,^granular coke settles readily making itpossibleto removethecoke continuously. asv a suspension in oil'from settler ,24 throughline 25 under ycontrol of valve J26intocolte,,c lroprollt,depressuringchamber 27 andvline 2 8 under control of valve 29. l

Accordingly, thencoked reactor efuent lows from coil 21throfujg`h line`2-3 tocole settler 24. In cokesettler 24a separation between ythe portionv ofthe coking coil eiiueht vaporous at ltern'p'eratures,of 700 to 1100 and the :portion liquid at those 4temp,eratures occurs. vaporous portion, li. (e., hydrogen and hydrocarbons boiling below about 650UF, at standard pressure pass frompokesettler ,24 through line V30, condenser 31 and liire'j32 toqgas-liquid lseparator 33.

vIn gas-liquid separator 33 vthe hydrogen and light hydrflirbons separate V'from Lthe condensed gasoline and ow from separator-33 through line 34 to the suction side of compressor 35.

Compressor 35 dischargesthe hydrogen-containing gas intoli'ne `36 at slightly above reactionfpressure. When necessaryror desirable, a portion of the gas in line 36 can be kvented to `fuel or sulfur recovery through line 37 under control of valve 38.

4Thegas discharged b y compressor 35 is hydrogencontaining recycle gas which ilows under reaction pressure from line 36 through line 6 `to coil 2 of heater 3 or directly to reactor 19 as described heretofore.

Returning to coke settler 24. The portion of ,the coking heater etiiuentwhich is liquid at the temperature and pressure existing in settler 24 contains the finely divided granular coke. The coke settles readily and is drawn olf as asludge or slurry 39. Thus, with valve 29 closed valve 26 in pipe 25 is opened and the slurry 39-at`the bottom of settler 24 flows into coke drop-out pot chamber 27. When pot 27 is filled valve 26 is closed and .plot 27 drained by opening valve'29 in pipe 28. The operation ,is repeated as often'as necessary to vkeep the leyelof the slurry below gas oil outlet 11 of coke settler 24.

lLiquid hydrocarbons substantially free of the line granular colse produced in the coking unit ow from coke Asettler' 24 Vthrough line 11 to condenser 40 and thence through line .41 to cracking units or fractionation units .or for other further treatment.

A `portion .of `the hot liquid hydrocarbon withdrawn from coke settler 24 through line 11 can be recycled to the hydrogenation .reactor through lines 14 and 15 under control of valve 12 by pump 13 as previously mentioned.

illustrative of one of the ymany modifications of the basic yconcept is the flow-sheet Figure 2.

`A heavy petroleum fraction, e. g., having an initial boiling point of at least 450 F. and a`10 percent point of at least 650 F. is pumped at reaction pressure from a source not shown through line 101. Recycle gas con taining at least percent hydrogen is pumped by compressor 102 under at least reactor pressure through lines 103a'nd 104 under control of valve 105 to line 101 where it is mixed with the fresh charge at the rate of 300 to 5000 s. c. f./b. of charge to form a charge mixture. The charge mixture flows through line 101 to coil 106 in heater 107 where the charge mixture is heated to reaction temperature. Alternatively, a portion or all of the recycle gas .can be pumped through vline 103 under control of valve 109 to line 110 and there mixed with the fresh charge at the rate of 300 to 5000 s. c. f./b.

`The heated charge mixture or charge stock flows at reaction temperature from coil 106 through line 110 to line 111 and thence to reactor 112.

Reactor 112 contains a bed of particle-form solid hydrogenation catalyst, preferably sulf-active hydrogena- The '4 tioncatalyst. VvIn reactorllZ the charge stock issubjected to mild hydrogenating conditions such as is provided by the following reaction conditions:

Temperature, F 600I to 800 Pressure, p. s. i. g 250 to 2000 Space velocity, v./ v./hr 1 to l() Hydrogen, s. c. f /b 300'to 5000 The hydrogenatedtand desulfurized charge together E with the hydrcgen-containingrgasforms.ameactor efuent which flows from reactor 112 through line 113. At this point the reactor euent can either-owthrou'gh line 113 under control of valve 114 tovliquid-gas separator 115 or be diverted through line 116 under control of valve 117 directly to line 118 and coking coil 119 in coking heater 120. v

When the reactor eil'luentflows alongtline 113 under control of valve 114 to liquidfgas separator 115, -the constituents of the reactor eiiuent boiling below `about 450 to 650 F. are vaporousunderreactor pressure and separate from the constituents ofthe reactor eluent liquidat reaction temperature and pressure. The vaporous and gaseous portion of the reactor etluent leaves liquid-gas separator 115 by way of line 121, passes through condenser 122 and ows through line 123`into accumulator 124.

In accumulator 124 the hydrogen vand light hydrocarbons separate from the higher boiling, i. e., gasoline boiling range Yhydrocarbons and flow through line 125 under control of valve 126 to recycle gas line 127 connected to vrthe suction side of recycle ygas compressor 102.

The gasoline is withdrawn from accumulator J124 through line 128 to line 129 where it is mixed with gasoline fractions vfrom other'sources in the unit. n

Returning to liquid-gas separator 115. The portion of the reactor effluent which is liquid at reaction 'itemperature and pressure ows from liquid-gas separator 115 through line 130 to line 118 and thence to coil v1'19 in coking heater 120. n

When the entire reactor eiluent is to 'be treated in the coking unit the lowfis as follows: from reactor-112 throughlines 113 and 116 under control of valve 117, thence along line 1-18 to coil 119.

When desirable a portion of the reactor etlluent can be sent directly to coil 119 by way of lines 116 and '118 and the balance sent indirectly to coil 119 by way vof separator 115 and lines 130 ,and 118.

In the coking unit the conditions are as follows:

Temperature, F. 800-'1200 Pressure, p. s. i. g v0-3'000 Hydrogen, s. c. f./b. 1 30-5000 1 From reactor 112 preferably,

It will be not-ed that the hot liquid hydrocarbon in Coker settler 134 substantially free from vthe fine, granular coke produced in lthe coking unit can be recycled to the vcoking heater 120 fby pump 136. Pump 136 draws hot liquid hydrocarbon from layer 135 in coke settler 134 through line 137 and discharges into line 138. From line 138 the hot liquid hydrocarbon in whole or in part can flow .through line 139 under control of valve 140 to line 118 and thence to coil 119 in admixture with reactor efliuent flowing through line 118.

The etliuent from coking heater 120 ows through line 131 to condenser 132 and thence through line 133 to coke settler 134. The coke produced is line and granular and suspended in the coking heater eiiuent. In coke settler 134 that portion of the coking heater efuent vaporous and/or gaseous at the temperature and pressure in the settler separates from the coke laden liquid portion. TheY vaporous and/or gaseous portion leaves settler 134 through line 141, passes through condenser 142 and line 143 to accumulator 144. In accumulator 144 the hydrogen and light hydrocarbons escape through line 145 to recycle gas line 127. The

components boiling in the gasoline range leave accumulator 14A through line 146 to be mixed with gasoline from other unit sources in lz'ne 129.

It will be observed that the liquid components of the coking heater eiuent form two layers, a lower layer 147 which is a slurry of line granular ycoke in liquid hydrocarbon and an upper layer 135 which is l1qu1d hydrocarbon of about the gas oil range substantially free from coke.

The coke can be withdrawn practically continuously as follows: with valve 148 closed, valve 149 is opened and the coke slurry flows through line 150 into pot or chamber 151 until the pot is filled. Valve 149 is then closed and valve 148 opened and the coke slurry drawn from pot 151 through line 152.

As has been mentioned hereinbefore, the liquid hydrocarbon 135 in settler 134 can be recycled to the coking heater 120. It can also be subjected to a more severe hydrogenation than that to which the charge was subjected in reactor 112.

Thus, liquid hydrocarbon is drawn by pump 136 from layer 135 in settler 134 through line 137. Pump 136 discharges into line 133 with valve 140 in line 139 closed and valve 153 in line 154 open the liquid hydrocarbon ows to line 155. Recycle gas containing hydrogen liows under pressure of compressor 102 -through lines 156 and `157 under control of valve 158 to line 155 where it Temperature, v F 700 to 1000 Pressure, p. s. i. g 500 to 3000 Space velocity, v./v./hr 0.1 to 5 Hydrogen, s. c. f./b. 300 to 5000 It will be noted that reaction conditions in reactor 159 are more severe than in reactor 112.

The effluent from reactor 159 ows through line 160 to liquid-gas separator 161.

In liquid-gas separator 161 those constituents of the eflluent of reactor 159 which boil below about 500 F. at normal pressure are in the vapor phase. phase portion of this effluent leaves separator 161 through line 162. The vapor phase effluent flows through line 162 to condenser 163 and thence through line 164 to accumulator 165 where hydrogen and light hydrocarbons separate from hydrocarbons boiling in the gasoline range. The hydrogen and light hydrocarbons iiow from accumulator 165 through line 166 and thence to line 127 to form with hydrogen-containing gases from other portions of the unit recycle gas.

That portion of the contents of accumulator 165 which is liquid at temperaturebelow about 500 F. and normal pressure, i. e., hydrocarbons in the gasoline boiling range flows from accumulator 165 through line 167 to line 129 and thence in admixture with gasoline from accumulators 124 and 144 flows to gasoline treatment, storage and/or distribution. Those skilled in the art will recognize that when desirable or necessary the three streams of gasoline from accumulators 124, 144 and 165 can be held separate or combined in any proportions.

Returning now to liquid-gas separator 161. The liquid portion of the etiluent from reactor 159 flows from separator 161 through line 168r to storage or distribution or further treatment. The liquid portion of the efuent from reactor 159 will usually boil in the gas oil range,

i. e., 500-650 F., and will ybe a highly saturated material of relatively low aromatic hydrocarbon content.

Alternatively a portion of the liquid portion of the eluent from reactor 159 ows from line 168 through line 169 under control of valve 170 to the suction side of pump 136 and thence to reactor 159 for further treat- The vapor ment therein in conjunction with the liquid hydrocarbon from layer in settler 134. In other words a portion of the liquid etiuent from reactor 159 is recycled thereto.

I claim:

1. A method of producing ne granular particles of petroleum coke which comprises mildly hydrogenating in a first zone a mineral oil fraction boiling above about 600 F. and substantially devoid of solid matter extraneous thereto in the presence of sulf-active hydrogenation catalyst at a temperature within the range of about 600 to about 800 F. at a pressure within the range of about 250 to about 3000 p. s. i. g. at a space velocity within the range of about 0.1 to about l0 v./v./hr. in the presence of about 300-to about 5000 s. c. f. of hydrogen per barrel of said mineral oil fraction to obtain a rst zone effluent substantially devoid of solid matter extraneous to said fraction comprising hydrogen and hydrocarbons boiling above about 600 F., passing said rst zone effluent substantially devoid of solid matter extraneous to said fraction through a coking zone at a temperature within the range of about 800 to about l200 F. at a pressure up to about 3000 p. s. i. g. in the presence of up to about 5000 s. c. f. of hydrogen per barrel to obtain an at least partially liquid coking zone effluent substantially devoid of solid matter extraneous to said mineral oil fraction comprising hydrogen, hydrocarbons boiling in the gasoline range and fine granular particles of coke suspended in liquid hydrocarbons boiling above the gasoline range including gas oil hydrocarbons, separating said hydrogen and hydrocarbons boiling in the gasoline range from a liquid fraction comprising fine granular particles of coke suspended in hydrocarbons boiling above the gasoline range and including hydrocarbons boiling in the gas oil range, stratifying said liquid fraction to obtain an upper liquid layer comprising hydrocarbons boiling in the gas oil range substantially devoid of said line granular particles of coke and a lower liquid layer comprising hydrocarbons boiling above the gasoline range and said fine granular particles of coke suspended therein, and separately withdrawing said upper liquid layer comprising hydrocarbons boiling in the gas oil range substantially devoid of said line granular particles of coke and said lower liquid layer comprising hydrocarbons boiling above the gasoline range and said ne granular particles of coke suspended therein.

2. The method set forth and described in claim 1 wherein the coking Zone eflluent is separated under a pressure substantially the same as that in the coking zone.

3. The method as set forth and described in claim l wherein at least part of the rst zone effluent is separated into a gaseous fraction comprising hydrogen and hydrocarbons boiling below the gas oil range and a liquid fraction comprising hydrocarbons boiling above the gasoline range, and wherein the aforesaid liquid fraction of said separated rst zone efluent is passed through said coking zone.

4. The method as set forth and described in claim 1 wherein at least part of the withdrawn upper liquid layer of the coking zone efliuent substantially devoid of fine granular particles of coke is recycled to the coking zone.

5. The method as set forth and described in claim l wherein at least'part ofthe withdrawn upper liquid layer of the coking zone effluent substantially devoid or" line, granular Yparticles of coke is subjected in a second hydrogenation zone to hydrogenation conditions more severe than exist in said rst zone and at a temperature within the range of about 700 to about 1000 F. at a vpressure within the range of about 500 to about 3000 p. s. i. g. at a space velocity within the range of about 0.1 to about 5 v./v./hr. in the presence of about 300 to about '5000 s. c. f. of hydrogen per barrel.

6. The method as setforth in claim 1 wherein atleast .-partlef the withdrawn yupperliquid layer 0f the-Collins i25111,@fusnt substantially dst/qid iQt .time granular Par- .tilespfsokeis subectsdin asssondlhydrtzesnation .2011s to hydrogenation conditions more severe than ,those in said first Zone and at .a temperature within ,the rangs oflabout 700 to about,1 000u1`". at apressure ,within `the irange of aboutO/Gtto about 3000 pgs. i. g. at v avspace velocity withiniherange of about,01,to,about 5 v./v./hr.

in ,the 4presence of Nabout 300 to about 5.000 ,s. VVC. f. of `hydroggm per barrel Aand in the Vprjesellce of a `catalyst comprising platinum Q11 :aluminaileast s -part 0f the Wthdrawn-,upperiliquid layerof-the cQliin/g zone etuentfsubstantally devoid ,of iin@ `granularrpartieles ,ofY coke is subjected I,in agse'cond hydrogena .tion zone-to hydrogenation conditions 4more severe than those in said rst zone at Ya ltemperature*within the range of about 700 -to about 1000 1l-. ata -pressuregwithin therange of about -5001to fabout3000p.s ifg. at a Space velocitywithinthe range of about Y0.1to abontvyS v./v./hr.

inthe presence o f about,3 00-;to about 5000sl c. `f. of

`hydrogen `per .barrel uand `in the presence of `a vcatalyst ,comprising ka `mixture `of oxides of cobalt and molyb- .denum 9. Ihe method .as ,set forth and described in `claim `1 `wherein ,the catalyst vin `the first zone comprises asulfactive 'hydrogenating catalyst, `and wherein Vat least a :part of the `Withdrawn upper liquid layer of the coki-ng fzone elluent substantially ldevoid of ne `granular particles ofvcoke is Asubjected in a second hydrogenation zone lto Yhydrogenation conditionsI more severe than ,those infsaid first zone at a temperature Within the rangeof labout 700 to about 1000 F. at a pressure withinthe range of labout 500 to about 3000 p. s. i. g. at a space velocity Within the range-of about 0.1 to about 5 v./v./hr.in the presence of about 300 to about 5000 s. c. f. ,per barrel ,and in t-ne presence Vof `particle form solid hydrogenating lcatalyst.

Reereuees Cited inthele of this patent UNlTED vSTATES PATENTS I 2,543,884 .Weikart` Mar. 6, 19 5 1 2,574,449 Lorne et al. Nov. :6, ,1951 2,655,464 Brown et al. Oct. 13, 1953 2,661,320 -Beckberger et al. Dec. 1, 19,53 2,717,855 ANicholson Sept. 13, 19-55 2,717,866 Deering et al Sept. .13, 1955 2,727,853 AHennig, Dec. 20, 1955 2,731,394 Adams et ai. Jan. 17, 19,56 2,738,307 Beckberger Mar. 13, 19,56 2,739,929 Madinger Mar. 27, V1956 2,768,939 YMason et a1. Oct. 30, 1956 

1. A METHOD OF PRODUCING FINE GRANULAR PARTICLES OF PETROLEUM COKE WHICH COMPRISES MILDLY HYDROGENATING IN A FIRST ZONE A MINERAL OIL FRACTION BOILING ABOVE ABOUT 600'' F. AND SUBSTANTIALLY DEVOID OF SOLID MATTER EXTRANEOUS THERETO IN THE PRESENCE OF SULF-ACTIVE HYDROGENATION CATALYST AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 600'' TO ABOUT 800'' F. AT A PRESSURE WITHIN THE RANGE OF ABOUT 250 TO ABOUT 3000 P.S.I.G. AT A SPACE VELOCITY WITHIN THE RANGE OF ABOUT 0.1 TO ABOUT 10 V./V./HR. IN THE PRESENCE OF ABOUT 300 TO ABOUT 5000 S.C.F. OF HYDROGEN PER BARREL OF SAID MINERAL OIL FRACTION TO OBTAIN A FIRST ZONE EFFLUENT SUBSTANTIALLY DEVOID OF SOLID MATTER EXTRANEOUS TO SAID FRACTION COMPRISING HYDROGEN AND HYDROCARBONS BOILING ABOVE ABOVE 600''F., PASSING SAID FIRST ZONE EFFLUENT SUBSTANTIALLY DEVOID OF SOLID MATTER EXTRANEOUS TO SAID FRACTION THROUGH A COKING ZONE AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 800'' TO ABOUT 1200''F. AT A PRESSURE UP TO ABOUT 3000 P.S.I.G. IN THE PRESENCE OF UP TO ABOUT 5000 S.C.F. OF HYDROGEN PER BARREL TO OBTAIN AN AT LEAST PARTIALLY LIQUID COKING ZONE EFFLUENT SUBSTANTIALLY DEVOID OF SOLID MATTER EXTRANEOUS TO SAID MINERAL OIL FRACTION COMPRISING HYDROGEN, HYDROCARBONS BOILING IN THE GASOLINE RAWNGE AND FINE GRANULAR PARTICLES OF COKE SUSPENDED IN LIQUID HYDROCARBONS BOILING ABOVE THE GASOLING RANGE INCLUDING GAS OIL HYDROCARBONS, SEPARATING SAID HYDROGEN AND HYDROCARBONS BOILING IN THE GASOLINE RANGE FROM A LIQUID FRACTION COMPRISING FINE GRANULAR PARTICLES OF COKE SUSPENDED IN HYDROCARBONS BOILING ABOVE THE GASOLINE RANGE AND INCLUDING HYDROCARBONS BOILING IN THE GAS OIL RANGE, STRATIFYING SAID LIQUID FRACTION TO ABTAIN AN UPPER LIQUID LAYER COMPRISING HYDROCARBONS BOILING IN THE GAS OIL RANGE SUBSTANTIALLY DEVOID OF SAID FINE GRANULAR PARTICLES OF COKE AND A LOWER LIQUID LAYER CO,PRISING HYDROCARBONS BOILING ABOVE THE GASOLINE RANGE AND SAID FINE GRANULAR PARTICLES OF COKE SUSPENDED THEREIN, AND SEPARATELY WITHDRAWING SAID UPPER LIQUID LAYER COMPRISING HYDROCARBONS BOILING IN THE GAS OIL RANGE SUBSTANTIALLY DEVOID OF SAID FINE GRANULAR PARTICLES OF COKE AND SAID LOWER LIQUID LAYER COMPRISING HYDROCARBONS BOILING ABOVE THE GASOLINE RANGE AND SAID FINE GRANULAR PARTICLES OF COKE SUSPENDED THEREIN. 